Using active ingredients such as metals and other biocides to prevent microbial contamination is an essential concern in daily life, in everywhere from, for example, surface areas in bathrooms, to surgical instruments, to wall paints. U.S. Pat. No. 6,905,698 B1, which is incorporated by reference herein in its entirety, generally discusses certain methods by which biocides can be used. Incorporating active ingredients into mineral-based fillers can ideally enhance antimicrobial capabilities of the finished products while additionally fulfilling, and without compromising, other filler functions. However, the effectiveness of the antimicrobial capabilities may decrease over time as the active ingredients leach out of the mineral-based fillers.
This invention generally relates to modified mineral-based fillers that can be incorporated into resins to produce a range of products, such as paints, clothing, polymers, surgical equipment, and coatings. Introducing active ingredients such as biocides into or with carrier materials has generally been disclosed for at least some variety of applications, such as in U.S. Pat. No. 5,648,086, in U.S. Patent Application Publication No. 2006/0035097, and in the use of celite as a biocide carrier. Introducing active ingredients such as metals into or with carrier materials has also generally been disclosed for at least some variety of applications, such as in U.S. Pat. Nos. 4,407,865 and 4,505,889, U.S. Patent Application Publication Nos. 2006/0180552 A1 and 2006/0246149 A1, in Japanese Patent Application Nos. 02215704 A2 and 2001010902 A2, as well as in Kevin D. Breese, Killer Fillers: Fillers with Antimicrobial Effects, 3d Int'l Conference for High Performance Fillers (Mar. 14-15, 2007).
Historically, however, active ingredients in mineral-based fillers leach out of the fillers during the life of the product in which they are incorporated, limiting the antimicrobial capabilities of the products, both in their initial antimicrobial capability and their continued antimicrobial capability as the active ingredient may diffuse from the mineral-based fillers. Current practices attempt to prolong the antimicrobial capabilities of different materials by slowing the diffusivity of the active ingredients in various ways. U.S. Pat. No. 5,180,585 and U.S. Patent Application No. 2006/0246149 A1 generally discusses a protective surface coating; U.S. Patent No. 6,905,698 B1 also generally discusses a protective surface coating or surface cleaning compositions; U.S. Pat. No. 4,656,057 attempts to solve the problem through use of porous or perforated membranes; EP-A-0602810, EP-A-0736249, GB-A-2235462 and GB-A-1590573 and U.S. Pat. No. 5,229,124 attempts to control the release of biocide to inhibit bacterial and fungal growth using sol gel chemistry to entrap the biocide but allow release thereof by diffusion from the hydrogel network; U.S. Pat. No. 4,579,779 involves encapsulation of organic liquids such as perfumes, food flavors, pesticides, and fungicides by combining liquid and silica in such a way that droplets of the organic liquid are encompassed within a shell of silica particles. U.S. Pat. No. 4,552,591 describes a composition intended to protect polymer dispersions used in oil field water treatment. Finally, modification of mineral-based fillers may have been generally disclosed, such as in U.S. Pat. Nos. 2,066,271 and 6,911,898. Doping materials for enhanced antimicrobial activity for plastics does not use mineral-based fillers, see, e.g., Masuda et al., Antimicrobial Activity of Silver-Doped Silica Glass Microspheres Prepared by Sol-Gel Method, J. BIOMED. MATER. RES. B. APPL. BIOMATER. 83B(1), 114-20 (2007). Indeed, none of those references appear to contemplate at least the modification of the mineral-based fillers, followed by thermal treatment such as calcination, as a method to enhance antimicrobial capabilities of the mineral-based fillers.